MON is active-standby, how about MGR? (active-active?)
The lower IP is active, rest are passive.
Although the MGR process is seemingly tied to the MON process, the two processes are really quite different. The MGR will only ever have 1 active process in the cluster; any other that you start (such as 2 others, each running on a MON node) will be passive. If you connect to MGR URL for one that is passive, it will redirect to the active MGR.